| Dental implant prosthesis has the advantages of not damaging natural teeth,high chewing efficiency after repair,and being beautiful and comfortable,and has become the best technical means for repairing dentition defects and defects.However,in clinical applications,due to the absorption and atrophy of alveolar bone after dentition defect and the factors such as periodontal disease and traumatic sequelae,the alveolar ridge is low and the bone mass is insufficient,which limits the application of planting and repair to some extent.Clinically,Many methods are often used to increase the bone mass in the defect area,and Guided bone regeneration(GBR)has become the only commonly used method in clinical practice.The basic principle of guided bone regeneration is to protect the blood clot by placing a mechanical barrier membrane,and to separate the bone defect from the surrounding connective tissue,ensuring that the bone forming cells preferentially enter the bone defect area,and after undergoing proliferation and differentiation,the bone repair is finally completed,and the bone is realized.regeneration.Nowadays,bio-barrier membranes are mainly classified into two categories: bio-non-absorbable membranes and bio-absorbable membranes.The biggest obstacle of non-absorbable membranes in clinical use is that they can not be degraded in vivo and need to be removed by second operation.Absorbable membranes often have some influence on their barrier function due to their unstable degradation cycle and weak mechanical strength.Therefore,it is clinically significant to find a kind of biodegradable material with high mechanical strength and simple processing technology to replace the existing commercial absorbable membrane.Magnesium alloy is an ideal bone regeneration material because of their biodegradability,good biocompatibility,good mechanical properties and osteogenic induction properties.ZK60(Mg-6Zn-0.5Zr)is a magnesium-zinc-zirconium alloy which has been extensively studied for its excellent degradability and is currently considered to be useful as a bone substitute material.However,the rate of degradation of the ZK60 alloy after implantation in the body is uncontrollable.If it is degraded too quickly,it can lead to adverse biological reactions,which affect its mechanical properties and lead to implant failure.Therefore,the modification of ZK60 alloy to make it have a controllable degradation rate has become a research hotspot.The introduction of rare earth elements can improve the mechanical properties and corrosion resistance of magnesium alloys.The addition of little rare earth elements to the ZK60 implanted magnesium alloy not only slows down its degradation but also improves its mechanical properties.And the research shows that the introduction of little rare earth will not cause harm to the body.Based on this design concept,ZNd K610(Mg-6Zn-Nd-0.5Zr)alloys were prepared by adding a small amount of Nd into ZK60.The mechanical and biological properties of the ZNd K610 alloys were studied to explore its application in guiding bone regeneration.Based on the above research concepts,this paper draws the following conclusions:1.Study on preparation technology and properties of rare earth modified magnesium alloysZNd K610 series of rare earth modified magnesium alloys were prepared by adding a small amount of Nd on the basis of the preparation process of ZK60.The microstructures,mechanical properties and corrosion resistance of ZNd K610 as-cast and extruded state were studied.It was found that the microstructures of ZNd K610 mainly changed from Mg Zn2 phase to W phase and T phase.The regenerative grains of extruded ZNd K610 alloy were obviously refined.The average grain size of extruded ZNd K610 alloy was about 460 nm,which was smaller than that of extruded ZK60 alloy(about 4.2 μm).In addition,the dominant intermetallic compounds(W and T phases)are thermodynamically stable and remain unchanged during extrusion.The tensile properties of extruded ZNd K610 were significantly improved at room temperature and high temperature(150 oC and 200 oC).2.Biological properties of ZNd K610 as an orthopaedic implant materialWe chose extruded ZNd K610 as the research material.Through cell proliferation test,cell cycle and cell adhesion test of MC3T3-E1 and MG63 cells in vitro,ZNd K610 showed good biocompatibility in vitro.Alkaline phosphatase activity test showed that ZNd K610 had osteogenic differentiation potential.The expression of related osteogenic genes and proteins was detected.It shows that it has obvious osteogenic function.3.Fluorescent labelled ion-doped hydroxyapatite nanorods as a model material for tracking the mechanism of osteoporosis and its application in ZNd K610Eu3+ ion fluorescence labeling method was used in hydroxyapatite nanocrystals.By adjusting the control factors of synthesis reaction,a series of hydroxyapatite nanocrystals with Eu3+ ion preferentially occupying Ca1 position were prepared.Through the analysis of structure and morphology,we found that the synthesis reaction under subcritical hydrothermal conditions can adjust the microstructure and mineralization orientation of hydroxyapatite by controlling the concentration of mineralizer and reaction temperature.We have determined the preferential occupation of Eu3+ at Ca1 site by IR,fluorescence excitation and emission spectra,and prepared a biocompatible hydroxyapatite coating on magnesium alloy by sol-gel spin coating process.The phenomenon that fluorescent labeled ions selectively occupy the crystal position of hydroxyapatite coatings can provide in situ labeling tools for the study of mineralization and demineralization mechanisms during osteogenesis and osteoclasts.In summary,we have developed rare earth modified magnesium alloys with better mechanical and degradable properties.Deposition of hydroxyapatite coating on implant surface has become a routine way to increase the contact between bone and implant materials and promote early osteogenesis.Through the fluorescence labeling method of hydroxyapatite coating,detailed experimental research and theoretical analysis were carried out in the aspects of material modification technology,activation of osteoblasts and in situ monitoring of osteogenesis and osteoclasts.It provides a research basis for guided bone regeneration technology based on magnesium alloy,and is expected to be used in clinical treatment of bone defects. |
PDF Full Text Request